locking axis in viewport navigation
You can use G (to move an object) then tap X (to move it just on x axis) or Y(y axis) and ...you guessed it Z to move it on the z-axis.
So Tap G-&gt;X to move it on global x-axis.
Tap G-&gt;X-&gt;X to move it on local x-axis. Analog with x, y.
For rotation is the same, just with R -&gt; X (rotates on global x-axis)
UPDATE:
you can navigate with these numpad keys: